Aircraft Towing Capacity Calculator: How Much Tug Do You Really Need?

Towing Capacity Fundamentals

Selecting the right tug for your aircraft fleet requires understanding more than just the published towing capacity.

Key Terms

• Drawbar Pull (DBP): The actual force the tug can exert at the hitch
• Gross Vehicle Weight (GVW): Tug weight + maximum load
• Towing Capacity: Maximum aircraft weight the tug can safely move
• Breakaway Force: Initial force needed to start moving a stationary aircraft

The Formula

Required Drawbar Pull = (Aircraft Weight × Rolling Resistance) + Grade Resistance + Acceleration Force

Typical Values

Grade Resistance

For ramp gradients (typically 0-5%):

• Grade Resistance = Aircraft Weight × sin(grade angle)
• At 3% grade: approximately 3% of aircraft weight

Practical Example

Moving a B737-800 (174,000 lbs) on dry concrete, flat surface:

• Rolling Resistance: 174,000 × 0.02 = 3,480 lbs
• Breakaway Force: ~10% more = 3,828 lbs
• Grade Resistance (3%): 174,000 × 0.03 = 5,220 lbs
• Total Required DBP: ~9,000 lbs

A TLD PB-1000 with 30,000 lbs DBP is more than adequate.

Quick Reference Table

Safety Margins

Always add 25% safety margin to your calculated requirement. This accounts for tire pressure variations, wet surfaces, and maintenance degradation.

Common Mistakes

• Using MTOW instead of ramp weight — Use actual operating weight (typically 90-95% of MTOW)
• Ignoring breakaway force — It's always higher than rolling friction
• Not planning for worst conditions — Wet/snowy ramps require significantly more capacity
• Oversizing — Too much tug is expensive and less maneuverable